Anthropic
Claude Haiku 5.5
Total Context
1M
Max Output
128K
Released
N/A
claude-fable-5.1Claude Fable 5 is Anthropic’s Mythos-class model designed for demanding reasoning, software engineering, knowledge work, visual analysis, and scientific research. Built for long-horizon agentic tasks, it can sustain planning and execution across complex workflows, analyze large codebases and documents, and refine its work over multiple steps. Claude Fable 5 is well suited to production applications that require advanced coding, research, professional analysis, and reliable autonomous task completion.
Context Window
1M tokens
Maximum Output
128K tokens
Release Date
Sep 1, 2026
Modalities
| Input Price | Output Price | Cache Read | Cache Create 5m |
|---|---|---|---|
| $10/M | $50/M | $0.25/M | $12.5/M |
Reasoning
Tool calling
Temperature parameter
Attachments
Knowledge Base
Endpoint Protocols
Claude Fable 5.1 combines demanding adaptive reasoning, long-running agentic coding, multimodal document understanding, and a one-million-token context.
Adaptive thinking is always active, with high effort by default for problems that require sustained analysis rather than immediate answers.
The model can work across entire codebases, write tests, recover from failed steps, and continue autonomous development over extended sessions.
Text and image inputs, including diagrams, charts, and tables in files or PDFs, can be analyzed within a one-million-token context.
Claude Fable 5.1 is suited to ambitious software projects, multi-stage knowledge work, long-running agents, and visual review of technical or business documents.
Implement codebase-wide features, conduct detailed code reviews, optimize performance, and verify results with model-written tests.
Conduct deep research, analyze large collections of material, and convert findings into documents, spreadsheets, or presentations ready for review.
Interpret diagrams, charts, and tables embedded in files or PDFs and connect their evidence to legal, financial, analytical, or architectural questions.
curl 'https://us-api.tokenhub.com/v1/messages' \
-X 'POST' \
-H "Authorization: Bearer $TOKENHUB_API_KEY"| Index score | ||
|---|---|---|
| Artificial Analysis Intelligence Index | Artificial Analysis broad capability aggregate | 58.1 |
| Artificial Analysis Coding Index | Artificial Analysis software task aggregate | 75.2 |
Metrics sourced from Artificial Analysis
Common questions about Claude Fable 5.1 and using it through TokenHub.
Claude Fable 5.1 is Anthropic’s active flagship model for demanding reasoning and long-horizon agentic work. It accepts text and image input and produces text output.
It is designed for long-running agentic coding, multistep research, and complex work with documents, spreadsheets, and slides.
It offers a 1-million-token context window, up to 128K output tokens, vision, tool use, and always-on adaptive thinking controlled through effort settings.
Anthropic labels its comparative latency as slower, and its per-token price is higher than Claude Opus 5 or Sonnet 5. Adaptive thinking cannot be disabled, and safety classifiers can return a refusal, so test latency, cost, and refusal handling.
Use the model identifier claude-fable-5-1 in your TokenHub API request, together with the endpoint and credentials shown in your TokenHub account. Test request formatting and response handling before production use.
Anthropic lists Claude Fable 5.1 as active on the Claude API, Amazon Bedrock, Google Cloud, Microsoft Foundry, and Claude Platform on AWS. Published Claude API rates are $10 per million input tokens, $50 per million output tokens, and $0.25 per million cache-read tokens; TokenHub billing may differ.
Choose it when difficult, long-horizon work needs more capability than your evaluations get from Claude Opus 5 at higher effort. For most routine workloads, Anthropic recommends starting with Claude Opus 5, while faster or cheaper models may be better for high-volume tasks.
Use one API key to access Claude Fable 5.1 and more AI models through TokenHub.
Claude Fable 5.1 Media and Demos
Verified official posts, videos, and community discussions about Claude Fable 5.1.
X (Twitter)
Claude ·
We’re introducing Claude Fable 5.1 and Claude Mythos 5.1. They're the world’s most advanced models for coding and knowledge work. https://t.co/8P9PSrWPi3
https://pbs.twimg.com/media/HRJlwmVWcAEyYzf.jpgView originalClaude ·
Fable 5.1 excels at complex, long-running tasks. And its research capabilities offer an early glimpse of how AI models will contribute to scientific progress. https://t.co/Yj0h0C3LdL
https://pbs.twimg.com/media/HRJl0VlW0AAS6DO.jpgView originalClaude ·
Cache reads with Fable 5.1 cost 75% less than Fable 5’s. This reduces the cost of the model in practice by around 25% for typical workloads, and up to 45% for highly agentic ones. https://t.co/uGjoKHcbOD
https://pbs.twimg.com/media/HRJhw1hXUAA_Uhm.pngView originalReddit
Introducing Claude Fable 5.1 and Claude Mythos 5.1
ClaudeOfficial ·
View originalUsed Fable 5.1 all day, here's what's actually different and what to try first
FragrantProgress8376 ·
Read full post
everyone's posting benchmarks. dont care. here's what I found after 3 hours with it, some of this will save you time what its good at big messy context. I dumped like 40 files in and asked "where does the money actually get calculated" and it walked back through the call chain instead of guessing from the filename. older models would pick the file called pricing.js and stop saying no. asked it to make a change and it went "you can, but this breaks the thing on line 200 that depends on it". first time a model has pushed back on me and been right long boring docs. contracts, terms of service, that 90 page pdf your accountant sent. ask it "what would you ask about if you were me" instead of "summarise this". way better output it stops. you ask a one line question you get a one line answer. sounds small. it isnt what its still bad at anything where the answer is on a webpage that changed last week. still have to tell it to go search it will still confidently do the wrong thing if your instructions were vague. its not psychic, its just less stupid writing in your voice. its better than before but if you dont give it 3 of your own examples it sounds like a very polite intern stuff worth trying today paste an error you've been ignoring for months. the one you're scared of give it a decision you're stuck on and say "argue the other side properly". its annoyingly good at this tell it "dont explain, just do it" at the top. saves a lot of scrolling the mythos thing is real, same model, fable just has safety stuff on top for dual use. if you're a normal person doing normal work you will not notice the difference what I'd skip dont use it as a search engine and dont ask it to "make this viral". it can't and neither can you anyway I've had 3 coffees and got more done than last week. back to it edit: no im not sponsored. wish I was, lads edit 2: yes its paid tier. do the maths on your hourly rate and stop asking
Fable 5.1 official prompting docs released
BasicsOnly ·
https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-fable-5-1
https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-fable-5-1View originalYouTube
Introducing Claude Fable 5.1
Anthropic
View originalClaude Fable 5.1 runs the forecast overnight
Claude
View originalDebugging across the whole stack with Claude Fable 5.1
Claude
View original